1. Technical Field
The present invention relates to a printer head, more particularly, to an inkjet printer head and a fabricating method thereof.
2. Description of the Related Art
Currently, there are ongoing attempts to apply inkjet techniques to a variety of fields, for example, the fields of biochips, metal wiring in PCB's, and color patterning in LCD's, etc. In thus applying inkjet techniques to new fields, the situation may arise where, unlike in the prior art of spraying low-viscosity ink drops on paper to form text or pictures, metal nanoparticles or highly viscous polymers, etc., are ejected onto a board of a special material.
Therefore, in order to apply inkjet techniques to several fields, the development of a suitable head is of critical importance. That is, the head should allow the ejection of ink droplets that are high in viscosity, it should provide high precision and frequency, it should not allow chemical reactions on the head structure caused by ink particles, and it should not allow the nozzles to be blocked. Thus, the development of an inkjet head is required that satisfies these conditions.
In general, inkjet printing is a technique of ejecting liquid ink onto paper for printing, where an inkjet print head has nozzles arranged that are about the size of a needlepoint, through which the ink is ejected. An inkjet printer can be grouped to the following types according to the method by which the ink is sprayed.
The bubble jet spray type ejects ink by using heating elements on the side wall of a minute tube to control the size of a bubble inside the nozzle. Increasing the heat on the heating elements creates a bubble inside the nozzle, where ink is sprayed when the bubble expands to its maximum size. When the heating of the heating elements is stopped after the spraying, the bubble disappears and the ink is replenished. Advantages of the bubble jet method are that it does not require an ink storage part, and that the sizes of the tubes and heating elements are very small, allowing a reduced size of the head. However, the bubble jet spraying method has the disadvantage that it is difficult to arrange the nozzles 2-dimensionally.
The thermal jet method is similar to the bubble jet type, but has a different position for the heating elements. That is, the thermal jet type has the heating elements arranged on the opposite or on the same side of the ink chamber as the nozzles, where ink is discharged by the vapor pressure created when the heated ink evaporates. The thermal jet type has the advantage that the arrangement of the heating elements and nozzles can be made 2-dimensional, so that the number of nozzles can be increased.
The piezoelectric spray type sprays ink by applying an impact from the rear side of the nozzle according to an inputted signal. A piezoelectric element, which changes shape according to an electric signal supplied as a driving power for ink ejection, is formed at an upper portion of the chamber where the ink is positioned. When a particular electric signal is supplied to deform the shape of the chamber, the ink surface at the end of the nozzle connected to the chamber is expanded, at which point the electric signal is controlled so as to abruptly pull back the ink surface, which causes the ink in front of the nozzle surface to be ejected due to inertia.
These inkjet printing techniques have been used mainly in the field of office automation (OA), and in marking packages and printing on clothing for industrial use, while application possibilities are gradually being extended with the development of functional ink, etc., that contains nano metal particles such as silver and nickel, etc.
However, while it is common in fabricating an inkjet printer head for ejecting ink or metallic or organic solvents, etc., to attach each plate member, such as for the membrane, chamber, ink storage part, and nozzles, etc., using adhesion layers, these adhesion layers are made of polymer materials, and are highly vulnerable to alcohol or other solvents used in ink. Also, as the plates are attached using several adhesion layers, the inkjet printer head is given a complicated composition and a complicated fabrication process.
That is, the conventional inkjet printer head, as illustrated in FIGS. 1 and 2, was fabricated by etching silicon boards, etc., and performing electrical plating to create the structure, or by mechanically processing stainless steel (SUS) and then stacking several layers. In the case of the prior art illustrated in FIG. 1, since the structure is formed by stacking, the numerous adhesion layers cause a reduced yield rate and a generally complicated process, and in the case of the prior art illustrated in FIG. 2, while there is an attempt to increase precision by the meticulous processing of a silicon board, the use of metal plating may induce foreign substances, and the adhesion layers may be vulnerable to ink.